The 49ers enter Thursday's NFL draft with perhaps the most talented roster in the league and more selections than any other team.

That should make this year's three-day draft more exciting than usual - expect plenty of trades - and give the 49ers a rare chance to sustain their recent success for the foreseeable future.

For general manager Trent Baalke, it's an opportunity - and a burden. With so many picks, this year's draft will be scrutinized for years to come. If he hits a home run, Baalke will create a legacy. If he comes up short, it will be considered a colossal waste.

Five questions the 49ers hope to answer over the next three days:

Can the 49ers find an heir apparent for Justin Smith?The last defensive lineman the 49ers picked in the first round was Kentwan Balmer in 2008. That experience was so unsettling that they've drafted just one defensive lineman since - Ricky Jean Francois in the seventh round in 2009. Instead, they've been content to fill backup defensive-line positions with undrafted players such as Demarcus Dobbs, Ian Williams and Tony Jerod-Eddie.

This year, though, the 49ers may have to make a stronger investment. Justin Smith's arm injury late last season provided a glimpse of what the defense would be like without him, and it wasn't pretty. Offenses gouged the 49ers through the air, and sack master Aldon Smith wasn't nearly as effective without Justin Smith next to him.